A germanium-on silicon (Ge-on-Si) photodetector is a key building block for optical interconnect and microwave photonics. A high-power and high-speed photodetector is particularly important for analog optical link with high gain, low noise floor, and high spurious-free dynamic range. However, there is a trade-off between the photodetector operation bandwidth and its saturation power. In general, a photodetector with high speed is usually designed with a low capacitance and a small carrier transit time, thus resulting in small dimensions. This causes the saturation power to be low due to the space charge effect. For conventional photodetectors, it is difficult to work at high speed with a high saturation power. Currently, a Ge photodetector is usually provided with only ˜5 mW saturation power and ˜10 GHz bandwidth.